Outpatient endometrial aspiration: an alternative to methotrexate for pregnancy of unknown location

Background Pregnancies of unknown location with abnormal beta-human chorionic gonadotropin trends are frequently treated as presumed ectopic pregnancies with methotrexate. Preliminary data suggest that outpatient endometrial aspiration may be an effective tool to diagnose pregnancy location, while also sparing women exposure to methotrexate. Objective The purpose of this study was to evaluate the utility of an endometrial sampling protocol for the diagnosis of pregnancies of unknown location after in vitro fertilization. Study Design A retrospective cohort study of 14,505 autologous fresh and frozen in vitro fertilization cycles from October 2007 to September 2015 was performed; 110 patients were diagnosed with pregnancy of unknown location, defined as a positive beta-human chorionic gonadotropin without ultrasound evidence of intrauterine or ectopic pregnancy and an abnormal beta-human chorionic gonadotropin trend (<53% rise or <15% fall in 2 days). These patients underwent outpatient endometrial sampling with Karman cannula aspiration. Patients with a beta-human chorionic gonadotropin decline ≥15% within 24 hours of sampling and/or villi detected on pathologic analysis were diagnosed with failing intrauterine pregnancy and had weekly beta-human chorionic gonadotropin measurements thereafter. Those patients with beta-human chorionic gonadotropin declines <15% and no villi identified were diagnosed with ectopic pregnancy and treated with intramuscular methotrexate (50 mg/m²) or laparoscopy. Results Across 8 years of follow up, among women with pregnancy of unknown location, failed intrauterine pregnancy was diagnosed in 46 patients (42%), and ectopic pregnancy was diagnosed in 64 patients (58%). Clinical variables that included fresh or frozen embryo transfer, day of embryo transfer, serum beta-human chorionic gonadotropin at the time of sampling, endometrial thickness, and presence of an adnexal mass were not significantly different between patients with failed intrauterine pregnancy or ectopic pregnancy. In patients with failed intrauterine pregnancy, 100% demonstrated adequate postsampling beta-human chorionic gonadotropin declines; villi were identified in just 46% (n=21 patients). Patients with failed intrauterine pregnancy had significantly shorter time to resolution (negative serum beta-human chorionic gonadotropin) after sampling compared with patients with ectopic pregnancy (12.6 vs 26.3 days; P<.001). Conclusion With the use of this safe and effective protocol of endometrial aspiration with Karman cannula, a large proportion of women with pregnancy of unknown location are spared methotrexate, with a shorter time to pregnancy resolution than those who receive methotrexate.